While conventional personal emergency breathing systems have been designed for use in fires and have addressed the problem of removing carbon monoxide and other toxic gases, i.e., cyanides, benzines and the like, they fail to provide a low-cost, one-piece system that integrates a protective hood, mouthpiece and filter in a single compact canister. Nor are such systems adaptable for specific environments, such as emergency life support systems for aircraft. In such conventional systems, the hood has been either an incidental independent feature of the filter system or has been attached in a separate package to be used or not used by choice. Such hoods have invariably been of a bulky design generally incorporating a solid heat-resistant material forming the main part of the body of the hood, severely restricting two-way communication, and provided with a transparent window of a size which substantially restricts vision and is subject, as a consequence of its limited area, to fogging. Such a design requires the hood to be packed and carried separately.
Prior art emergency breathing systems typically exhaust exhaled gases via a one-way valve to atmosphere, or back into the filter via the mouth or mouth/nose piece. Consequently, prior art systems have required a rubber/plastic face forming a nose/mouth cover or a mouthpiece and noseclip. These devices are not efficient, particularly when used on bearded or children's faces. Similarly, mouthpieces with a separate noseclip are inconvenient and, unless placed properly on the nose, are subject to being easily dislodged and lost.
Prior art systems are often bulky, sometimes require sizing for fitting particular individuals, and generally are not conductive to easy or practical day-to-day carriage or storage. Prior art systems also have employed a variety of fitting methods generally relying on multiple or single-strap arrangements requiring individual adjustment to ensure a proper airtight fit to the individual user. In an emergency or panic situation, such methods are time-consuming and sometimes confusing to use, especially in the case of multiple-strap arrangements. Certain prior art systems do not provide a protective hood or face mask and are complicated in design or use or both. Additionally, such systems are expensive to manufacture, do not lend themselves to a low retail cost, and hence are effectively precluded from a cost standpoint from prepositioning in the necessary numbers in populated areas. Nor are those systems adaptable for use in specific environments, for example, in an emergency personal life support system for an aircraft.